Abstract
Water oxidation is the key kinetic bottleneck of photoelectrochemical devices for fuel synthesis. Despite advances in the identification of intermediates, elucidating the catalytic mechanism of this multi-redox reaction on metal–oxide photoanodes remains a significant experimental and theoretical challenge. Here, we report an experimental analysis of water oxidation kinetics on four widely studied metal oxides, focusing particularly on haematite. We observe that haematite is able to access a reaction mechanism that is third order in surface-hole density, which is assigned to equilibration between three surface holes and M(OH)–O–M(OH) sites. This reaction exhibits low activation energy (Ea ≈ 60 meV). Density functional theory is used to determine the energetics of charge accumulation and O–O bond formation on a model haematite (110) surface. The proposed mechanism shows parallels with the function of the oxygen evolving complex of photosystem II, and provides new insights into the mechanism of heterogeneous water oxidation on a metal oxide surface.
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Data availability
The complete optical and electrochemical dataset is available at http://zenodo.org with the identifier 10.5281/zenodo.851635.
References
Zhu, S. & Wang, D. Photocatalysis: basic principles, diverse forms of implementations and emerging scientific opportunities. Adv. Energy Mater. 17, 1700841 (2017).
Berardi, S. et al. Molecular artificial photosynthesis. Chem. Soc. Rev. 43, 7501–7519 (2014).
Walter, M. G. et al. Solar water splitting cells. Chem. Rev. 110, 6446–6473 (2010).
Lewis, N. S. & Nocera, D. G. Powering the planet: chemical challenges in solar energy utilization. Proc. Natl Acad. Sci. USA 103, 15729–15735 (2006).
Sun, K. et al. A comparison of the chemical, optical and electrocatalytic properties of water-oxidation catalysts for use in integrated solar-fuel generators. Energy Environ. Sci. 10, 987–1002 (2017).
McCrory, C. C. L., Jung, S., Peters, J. C. & Jaramillo, T. F. Benchmarking heterogeneous electrocatalysts for the oxygen evolution reaction. J. Am. Chem. Soc. 135, 16977–16987 (2013).
Kärkäs, M. D. & Åkermark, B. Water oxidation using earth-abundant transition metal catalysts: opportunities and challenges. Dalton Trans. 45, 14421–14461 (2016).
Blakemore, J. D., Crabtree, R. H. & Brudvig, G. W. Molecular catalysts for water oxidation. Chem. Rev. 115, 12974–13005 (2015).
Llobet, A. Molecular Water Oxidation Catalysis: A Key Topic for New Sustainable Energy Conversion Schemes (2014, Wiley).
Dau, H. et al. The mechanism of water oxidation: from electrolysis via homogeneous to biological catalysis. ChemCatChem 2, 724–761 (2010).
Shinagawa, T., Garcia-Esparza, A. T. & Takanabe, K. Insight on Tafel slopes from a microkinetic analysis of aqueous electrocatalysis for energy conversion. Sci. Rep. 5, 13801 (2015).
Gerischer, H. The impact of semiconductors on the concepts of electrochemistry. Electrochim. Acta 35, 1677–1699 (1990).
Francàs, L., Mesa, C. A., Pastor, E., Le Formal, F. & Durrant, J. R. in Advances in Photoelectrochemical Water Splitting: Theory, Experiment and Systems Analysis (eds Tilley, S. D., Lany, S. & van de Krol, R.) Ch. 5 (Royal Society of Chemistry, 2018).
Pastor, E. et al. Spectroelectrochemical analysis of the mechanism of (photo)electrochemical hydrogen evolution at a catalytic interface. Nat. Commun. 8, 14280 (2017).
Mesa, C. A. et al. Kinetics of photoelectrochemical oxidation of methanol on hematite photoanodes. J. Am. Chem. Soc. 139, 11537–11543 (2017).
Le Formal, F. et al. Rate law analysis of water oxidation on a hematite surface. J. Am. Chem. Soc. 137, 6629–6637 (2015).
Ma, Y. et al. Rate law analysis of water oxidation and hole scavenging on a BiVO4 photoanode. ACS Energy Lett. 1, 618–623 (2016).
Kafizas, A. et al. Water oxidation kinetics of accumulated holes on the surface of a TiO2 photoanode: a rate law analysis. ACS Catal. 7, 4896–4903 (2017).
Pesci, F. M., Cowan, A. J., Alexander, B. D., Durrant, J. R. & Klug, D. R. Charge carrier dynamics on mesoporous WO3 during water splitting. J. Phys. Chem. Lett. 2, 1900–1903 (2011).
Barroso, M., Pendlebury, S. R., Cowan, A. J. & Durrant, J. R. Charge carrier trapping, recombination and transfer in hematite (α-Fe2O3) water splitting photoanodes. Chem. Sci. 4, 2724–2734 (2013).
Roger, I., Shipman, M. A. & Symes, M. D. Earth-abundant catalysts for electrochemical and photoelectrochemical water splitting. Nat. Rev. Chem. 1, 0003 (2017).
Rosser, T. E., Gross, M. A., Lai, Y.-H. & Reisner, E. Precious-metal free photoelectrochemical water splitting with immobilised molecular Ni and Fe redox catalysts. Chem. Sci. 7, 4024–4035 (2016).
Zhang, Y. et al. Rate-limiting O−O bond formation pathways for water oxidation on hematite photoanode. J. Am. Chem. Soc. 140, 3264–3269 (2018).
Schulze, M., Kunz, V., Frischmann, P. D. & Würthner, F. A supramolecular ruthenium macrocycle with high catalytic activity for water oxidation that mechanistically mimics photosystem II. Nat. Chem. 8, 576–583 (2016).
Kafizas, A. et al. Optimizing the activity of nanoneedle structured WO3 photoanodes for solar water splitting: direct synthesis via chemical vapor deposition. J. Phys. Chem. C 121, 5983–5993 (2017).
Cowan, A. J., Leng, W., Barnes, P. R. F., Klug, D. R. & Durrant, J. R. Charge carrier separation in nanostructured TiO2 photoelectrodes for water splitting. Phys. Chem. Chem. Phys. 15, 8772 (2013).
Ma, Y., Le Formal, F., Kafizas, A., Pendlebury, S. R. & Durrant, J. R. Efficient suppression of back electron/hole recombination in cobalt phosphate surface-modified undoped bismuth vanadate photoanodes. J. Mater. Chem. A 3, 20649–20657 (2015).
Wang, X. H. et al. Pyrogenic iron(iii)-doped TiO2 nanopowders synthesized in RF thermal plasma: phase formation, defect structure, band gap and magnetic properties. J. Am. Chem. Soc. 127, 10982–10990 (2005).
Wahlström, E. et al. Bonding of gold nanoclusters to oxygen vacancies on rutile TiO2 (110). Phys. Rev. Lett. 90, 026101 (2003).
Zandi, O. & Hamann, T. W. Determination of photoelectrochemical water oxidation intermediates on haematite electrode surfaces using operando infrared spectroscopy. Nat. Chem. 8, 778–783 (2016).
Cowan, A. J. et al. Activation energies for the rate-limiting step in water photooxidation by nanostructured α-Fe2O3 and TiO2. J. Am. Chem. Soc. 133, 10134–10140 (2011).
Kosmulski, M. pH-dependent surface charging and points of zero charge. IV. Update and new approach. J. Colloid Interface Sci. 337, 439–448 (2009).
Aharon, E. & Toroker, M. C. The effect of covering Fe2O3 with a Ga2O3 overlayer on water oxidation catalysis. Catal. Lett. 147, 2077–2082 (2017).
Yatom, N., Elbaz, Y., Navon, S. & Caspary Toroker, M. Identifying the bottleneck of water oxidation by ab initio analysis of in situ optical absorbance spectrum. Phys. Chem. Chem. Phys. 19, 17278–17286 (2017).
Seriani, N. Ab initio simulations of water splitting on hematite. J. Phys. Condens. Matter 29, 463002 (2017).
Grave, D. A., Yatom, N., Ellis, D. S., Toroker, M. C. & Rothschild, A. The ‘rust’ challenge: on the correlations between electronic structure, excited state dynamics and photoelectrochemical performance of hematite photoanodes for solar water splitting. Adv. Mater. 30, 1706577 (2018).
Nguyen, M.-T., Seriani, N. & Gebauer, R. Back cover: defective α-Fe2O3 (0001): an ab initio study. ChemPhysChem 15, 3136–3136 (2014).
Zhang, X., Klaver, P., Van Santen, R., Van De Sanden, M. C. M. & Bieberle-Hütter, A. Oxygen evolution at hematite surfaces: the impact of structure and oxygen vacancies on lowering the overpotential. J. Phys. Chem. C 120, 18201–18208 (2016).
Kay, A., Cesar, I. & Grätzel, M. New benchmark for water photooxidation by nanostructured α-Fe2O3 films. J. Am. Chem. Soc. 128, 15714–15721 (2006).
Cornuz, M., Grätzel, M. & Sivula, K. Preferential orientation in hematite films for solar hydrogen production via water splitting. Chem. Vap. Depos. 16, 291–295 (2010).
Yamada, H., Siems, W. F., Koike, T. & Hurst, J. K. Mechanisms of water oxidation catalyzed by the cis,cis-[(bpy)2Ru(OH2)]2O4+ ion. J. Am. Chem. Soc. 126, 9786–9795 (2004).
Pham, H. H., Cheng, M.-J., Frei, H. & Wang, L.-W. Surface proton hopping and fast-kinetics pathway of water oxidation on Co3O4 (001) surface. ACS Catal. 6, 5610–5617 (2016).
Askerka, M., Brudvig, G. W. & Batista, V. S. The O2-evolving complex of photosystem II: recent insights from quantum mechanics/molecular mechanics (QM/MM), extended X-ray absorption fine structure (EXAFS), and femtosecond X-ray crystallography data. Acc. Chem. Res. 50, 41–48 (2017).
Amin, M. et al. Proton-coupled electron transfer during the S-state transitions of the oxygen-evolving complex of photosystem II. J. Phys. Chem. B 119, 7366–7377 (2015).
Rossmeisl, J. et al. Electrolysis of water on oxide surfaces. J. Electroanal. Chem. 607, 83–89 (2007).
Siegbahn, P. E. M. O–O bond formation in the S4 state of the oxygen-evolving complex in photosystem II. Eur. J. Chem. A 12, 9217–9227 (2006).
Siegbahn, P. E. M. Water oxidation mechanism in photosystem II, including oxidations, proton release pathways, O–O bond formation and O2 release. Biochim. Biophys. Acta 1827, 1003–1019 (2013).
Pecoraro, V. L., Baldwin, M. J., Caudle, M. T., Hsieh, W.-Y. & Law, N. A. A proposal for water oxidation in photosystem II. Pure Appl. Chem. 70, 925–929 (1998).
Vrettos, J. S., Limburg, J. & Brudvig, G. W. Mechanism of photosynthetic water oxidation: combining biophysical studies of photosystem II with inorganic model chemistry. Biochim. Biophys. Acta 1503, 229–245 (2001).
Sproviero, E. M., Gascó, J. A., Mcevoy, J. P., Brudvig, G. W. & Batista, V. S. Quantum mechanics/molecular mechanics study of the catalytic cycle of water splitting in photosystem II. J. Am. Chem. Soc. 130, 3428–3442 (2008).
Barber, J. A mechanism for water splitting and oxygen production in photosynthesis. Nat. Plants 3, 17041 (2017).
Barber, J. Photosystem II: the water splitting enzyme of photosynthesis and the origin of oxygen in our atmosphere. Q. Rev. Biophys. 49, e14 (2017).
Li, X. & Siegbahn, P. E. M. Water oxidation for simplified models of the oxygen‐evolving complex in photosystem II. Chem. A Eur. J. 21, 18821–18827 (2015).
Klauss, A., Haumann, M. & Dau, H. Seven steps of alternating electron and proton transfer in photosystem II water oxidation traced by time-resolved photothermal beam deflection at improved sensitivity. J. Phys. Chem. B 119, 2677–2689 (2015).
Vinyard, D. J. & Brudvig, G. W. Progress toward a molecular mechanism of water oxidation in photosystem II. Annu. Rev. Phys. Chem. 68, 101–116 (2017).
Zhang, M. & Frei, H. Water oxidation mechanisms of metal oxide catalysts by vibrational spectroscopy of transient intermediates. Annu. Rev. Phys. Chem. 68, 209–231 (2017).
Zhang, M., De Respinis, M. & Frei, H. Time-resolved observations of water oxidation intermediates on a cobalt oxide nanoparticle catalyst. Nat. Chem. 6, 362–367 (2014).
Yang, K. R. et al. Solution structures of highly active molecular Ir water-oxidation catalysts from density functional theory combined with high-energy X-ray scattering and EXAFS spectroscopy. J. Am. Chem. Soc. 138, 5511–5514 (2016).
Gamba, I., Codolà, Z., Lloret-Fillol, J. & Costas, M. Making and breaking of the O–O bond at iron complexes. Coord. Chem. Rev. 334, 2–24 (2017).
Tinberg, C. E. & Lippard, S. J. Dioxygen activation in soluble methane monooxygenase. Acc. Chem. Res. 280, 280–288 (2011).
Shu, L. et al. An Fe2IVO2 diamond core structure for the key intermediate Q of methane monooxygenase. Science 275, 515–518 (1997).
Friedle, S., Reisner, E. & Lippard, S. J. Current challenges of modeling diiron enzyme active sites for dioxygen activation by biomimetic synthetic complexes. Chem. Soc. Rev. 39, 2768–2779 (2010).
Acknowledgements
J.R.D. acknowledges financial support from the European Research Council (project Intersolar 291482) and H2020 project A-LEAF (732840). C.A.M. thanks COLCIENCIAS (call 568) for funding. L.F. thanks the EU for a Marie Curie fellowship (658270) and E.P. thanks the EPRSC for a DTP scholarship. V.S.B. acknowledges support from the Air Force Office of Scientific Research (AFSOR) grant no. FA9550-17-0198 and high performance computer time from the National Energy Research Scientific Computing Center (NERSC). P.G.B. acknowledges “la Caixa” foundation for the PhD grant. A.K. thanks Imperial College for a Junior Research Fellowship. M.G. acknowledges support from the Swiss National Science Foundation (project 140709) and Swiss Federal Office for Energy (project PECHouse 3; contract no. SI/500090–03). T.E.R. thanks the EPSRC for a DTC studentship and E.R. the Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy, and the National Foundation for Research, Technology and Development) and the OMV Group for financial support. M.T.M. acknowledges the Helmholtz Association’s Initiative and Networking Fund.
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C.A.M. and L.F. contributed equally to this work. All authors discussed the results and commented on and revised the manuscript. C.A.M., L.F. and J.R.D. conceived and designed the experiments. K.R.Y., P.G. and V.S.B. contributed the DFT work. E.P., Y.M., A.K., T.E.R., M.T.M., E.R. and M.G. contributed materials and data.
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Supplementary Figs. 1–16, Tables 1–3, experimental methods, density functional theory calculations, optical and photoelectrochemical characterization of the materials used, supporting data for the activation energy calculation as well as the kinetic isotope effect and the pH dependence studies and discussion of the first-order mechanism and optimized geometries.
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Optimized geometries for the density functional theory calculations.
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Mesa, C.A., Francàs, L., Yang, K.R. et al. Multihole water oxidation catalysis on haematite photoanodes revealed by operando spectroelectrochemistry and DFT. Nat. Chem. 12, 82–89 (2020). https://doi.org/10.1038/s41557-019-0347-1
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DOI: https://doi.org/10.1038/s41557-019-0347-1
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